Polymer, friction reducer for lubricating oil, and lubricating oil composition

Abstract

To provide a polymer which provides a polymer lubricant additive with a high friction reduction effect, a friction reduction agent for a lubricant, and a lubricant composition.SOLUTION: The polymer has a backbone polymer structure and a side chain polymer structure. The side chain polymer structure includes constitutional units derived from alkyl(meth)acrylate (a) with an alkyl group carbon number of 11 to 30. At least one of the backbone polymer structure and the side chain polymer structure includes constitutional units derived from (meth)acrylate (b) represented by the following general formula (1). In the formula (1), R1 represents a hydrogen atom or methyl group, and R2 represents an organic group containing a hydrogen atom or polar group, provided that the organic group containing a polar group does not include an alkoxy-alkyl group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polymer for use in engine oils, etc., a friction reducer for lubricating oils, and a lubricating oil composition. This application claims priority based on Japanese Patent Application No. 2022-143787, filed on September 9, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Lubricating oils, such as automobile engine oils and driveline oils, contain various friction reducers to reduce energy loss due to friction and to extend the life of equipment by preventing seizure. In recent years, the viscosity of lubricating oils has been reduced in order to reduce fuel consumption, and the load on the contact surfaces between metals has become more severe, making the role of friction reducers even more important. Examples of friction reducers include oiliness improvers such as long-chain fatty acid esters and fatty acid amides, antiwear agents such as phosphate esters and zinc dithiophosphates, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and friction modifiers such as organic molybdenum compounds. However, depending on the conditions of use and the environment of use, these additives alone may not be sufficient to reduce friction. In order to overcome this problem, studies are being conducted on the use of polymer materials as friction reducers. For example, Patent Document 1 discloses that comb polymers containing repeating units derived from polyolefin-based macromonomers and repeating units derived from low-molecular-weight monomers can be suitably used as friction modifiers (friction improvers). Patent Document 2 also discloses that (meth)acrylic graft copolymers can be suitably used as friction modifiers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-502344 [Patent Document 2] JP 2022-113676 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the methods described in Patent Documents 1 and 2 are insufficient in reducing friction.

[0005] An object of the present invention is to provide a polymer, and to provide a polymer that can be used to provide a polymer lubricating oil additive, a friction reducer for lubricating oil, and a lubricating oil composition having a high friction reducing effect. [Means for solving the problem]

[0006] [1] A polymer having a main chain structure and a side chain polymer structure, the side chain polymer structure contains a structural unit derived from an alkyl(meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms, A polymer, wherein at least one of the main chain polymer structure and the side chain polymer structure contains a structural unit derived from a (meth)acrylate (b) represented by the following general formula (1): [ka] (In the formula, R 1 is a hydrogen atom or a methyl group, and R 2 represents a hydrogen atom or an organic group containing a polar group. However, the organic group containing a polar group does not include an alkoxyalkyl group. [2] The polymer according to [1], wherein the polar group of the (meth)acrylate (b) is a hydroxyl group, a carboxy group, an amino group or an amide group. [3] The polymer according to [1] or [2], wherein the polar group of the (meth)acrylate (b) is a hydroxyl group. [4] The polymer according to any one of [1] to [3], further comprising a structural unit derived from an alkyl(meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms. [5] The polymer according to any one of [1] to [4], wherein the main chain polymer structure contains a structural unit derived from an alkyl(meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms. [6] The polymer according to any one of [1] to [5], wherein the proportion of the main chain polymer structure is preferably 25 to 98 mass%, more preferably 30 to 95 mass%, and still more preferably 40 to 90 mass%, based on the total mass of the polymer. [7] The polymer according to any one of [1] to [6], wherein a proportion of the side chain polymer structure is preferably from 2 to 75 mass%, more preferably from 5 to 70 mass%, and still more preferably from 10 to 60 mass%, based on the total mass of the polymer. [8] The copolymer according to any one of [1] to [7], wherein the alkyl (meth)acrylate (a) is preferably a linear or branched alkyl (meth)acrylate having 11 to 20 carbon atoms, more preferably a linear or branched alkyl methacrylate having 11 to 20 carbon atoms, still more preferably a linear or branched alkyl methacrylate having 11 to 18 carbon atoms, and particularly preferably a linear or branched alkyl methacrylate having 12 to 14 carbon atoms. [9] The polymer according to any one of [1] to [8], wherein the content of the structural unit derived from the alkyl (meth)acrylate (a) is preferably 30 to 100 mass%, more preferably 50 to 100 mass%, and even more preferably 80 to 99 mass%, based on the total mass of the side chain polymer structure.

[10] The polymer according to any one of [1] to [9], wherein the content of the structural unit derived from the alkyl (meth)acrylate (a) is preferably 20 to 90 mass%, more preferably 25 to 85 mass%, and even more preferably 30 to 80 mass%, based on the total mass of the polymer.

[11] The polymer according to any one of [1] to

[10] , wherein the polar group of the (meth)acrylate (b) is preferably a hydroxyl group, a carboxy group, an aliphatic heterocycle having 2 to 6 carbon atoms, an aromatic heterocycle having 4 to 10 carbon atoms, an alkoxysilyl group, a trialkoxysilyl group having 3 to 9 carbon atoms, a phosphate group, a phosphate ester group, an amino group, or an amide group; more preferably a hydroxyl group, a carboxy group, an amino group, or an amide group; and even more preferably a hydroxyl group.

[12] The (meth)acrylate (b) preferably has a total carbon number of 3 to 10, more preferably 3 to 9, and further preferably 3 to 8. The polymer according to any one of [1] to

[11] .

[13] The copolymer according to any one of [1] to

[12] , wherein the content of the structural unit derived from the (meth)acrylate (b) is preferably from 0.01 to 20% by mass, more preferably from 0.05 to 15% by mass, even more preferably from 0.1 to 5% by mass, and particularly preferably from 0.5 to 3% by mass, relative to the total mass of the polymer.

[14] The polymer according to any one of [1] to

[13] , further comprising a structural unit derived from an alkyl(meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms.

[15] The polymer according to any one of [1] to

[14] , further comprising a structural unit derived from an alkyl(meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms, wherein the alkyl(meth)acrylate (c) is preferably an alkyl(meth)acrylate having 1 to 4 carbon atoms, more preferably an alkyl acrylate having 1 to 4 carbon atoms, and even more preferably n-butyl acrylate.

[16] The polymer according to any one of [1] to

[15] , further comprising a structural unit derived from an alkyl (meth)acrylate (c) having 1 to 10 carbon atoms in the alkyl group, wherein the content of the structural unit derived from the alkyl (meth)acrylate (c) is preferably from 20 to 95 mass%, more preferably from 30 to 90 mass%, and even more preferably from 45 to 80 mass%, relative to the total mass of the polymer.

[17] The polymer according to any one of [1] to

[16] , wherein the total content of the structural units derived from the alkyl (meth)acrylate (a), the structural units derived from the (meth)acrylate (b) represented by the general formula (1), and the structural units derived from the alkyl (meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass%, relative to the total mass of the polymer.

[18] The main chain polymer structure contains a constituent unit derived from a vinyl radical polymerizable monomer (m1), and at least a part of the constituent units derived from the vinyl radical polymerizable monomer (m1) is a constituent unit derived from the (meth)acrylate (b). The polymer according to any one of [1] to

[17] .

[19] The polymer according to any one of [1] to

[18] , wherein the side chain polymer structure contains a constituent unit derived from a macromonomer (M).

[20] The polymer according to

[19] , wherein the macromonomer (M) contains a structural unit derived from an alkyl(meth)acrylate (a) having 11 to 30 carbon atoms in the alkyl group.

[21] The polymer according to

[19] or

[20] , wherein the macromonomer (M) has a structure represented by the following formula (2): [ka] (In the formula, X 1 ~X n-1 each independently represents a hydrogen atom, a methyl group, or CHOH; Y 1 ~Y n each independently represents X bonded to a vinyl group of the vinyl radical polymerizable monomer (m2) which is a monomer constituent unit of the macromonomer (M). 1 ~X n-1 Z represents a terminal group, and n represents an integer of 2 to 10,000.

[22] The polymer according to any one of

[18] to

[21] , wherein the vinyl-based radically polymerizable monomer (m1) comprises a (meth)acrylate (b) represented by the general formula (1) and an alkyl (meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms.

[23] The polymer according to any one of

[18] to

[22] , wherein the vinyl radically polymerizable monomer (m2) contains the alkyl (meth)acrylate (a).

[24] The polymer according to any one of

[19] to

[23] , wherein the content of the structural unit derived from the alkyl (meth)acrylate (a) is preferably 80 to 100 mass%, more preferably 85 to 99.9 mass%, further preferably 90 to 99.8 mass%, and particularly preferably 95 to 99.5 mass%, based on the total mass of the macromonomer (M).

[25] The polymer according to any one of

[19] to

[24] , wherein the content of structural units derived from an alkyl (meth)acrylate (c) having an alkyl group with 1 to 10 carbon atoms, relative to the total mass of the macromonomer (M), is preferably more than 0 mass% and 20 mass% or less, more preferably 0.1 to 15 mass%, even more preferably 0.2 to 10 mass%, and particularly preferably 0.5 to 5 mass%.

[26] The polymer according to any one of

[18] to

[25] , wherein the ratio represented by [the content of the structural units derived from the alkyl (meth)acrylate (c) having a carbon number of 1 to 10 in the alkyl group] / [the content of the structural units derived from the alkyl (meth)acrylate (a)] is preferably 0.001 to 3.5, more preferably 0.002 to 3.0, and even more preferably 0.005 to 2.6.

[27] The polymer according to any one of

[19] to

[26] , wherein the content of the constitutional unit derived from the macromonomer (M) is preferably 1 to 70 mass%, more preferably 2 to 60 mass%, and still more preferably 5 to 50 mass%, based on the total mass of the polymer.

[28] The polymer according to any one of

[19] to

[27] , wherein the macromonomer (M) has a mass average molecular weight (Mw) measured by gel permeation chromatography of preferably 2,000 to 100,000, more preferably 3,000 to 80,000, further preferably 4,000 to 50,000, and particularly preferably 5,000 to 30,000.

[29] The polymer according to any one of

[19] to

[28] , wherein the macromonomer (M) has a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of preferably 500 to 30,000, more preferably 1,000 to 25,000, further preferably 2,000 to 20,000, and particularly preferably 3,000 to 16,000.

[30] The polymer according to any one of

[19] to

[29] , wherein the molecular weight distribution (Mw / Mn) of the macromonomer (M) measured by gel permeation chromatography is preferably from 1.0 to 5.0, more preferably from 1.3 to 3.0, and even more preferably from 1.5 to 2.5.

[31] The polymer according to any one of [1] to

[30] , wherein the mass average molecular weight (Mw) of the polymer measured by GPC is preferably 10,000 or more and 500,000 or less, more preferably 15,000 or more and 300,000 or less, and even more preferably 20,000 or more and 200,000 or less.

[32] The polymer according to any one of [1] to

[31] , wherein the number average molecular weight (Mn) of the polymer measured by gel permeation chromatography (GPC) is preferably 5,000 or more and 100,000 or less, more preferably 10,000 or more and 80,000 or less, and even more preferably 15,000 or more and 50,000 or less.

[33] The polymer according to any one of [1] to

[32] , wherein the molecular weight distribution (Mw / Mn) of the polymer as measured by gel permeation chromatography (GPC) is preferably 1.0 or more and 15 or less, more preferably 2.0 or more and 10 or less, and even more preferably 3.0 or more and 8.0 or less.

[34] The polymer according to any one of [1] to

[33] , wherein a friction coefficient measured at 40°C using an SRV5 testing machine (manufactured by Optimol Instruments Pruftechnik GmbH) in a base oil solution containing 2 mass% of the polymer is preferably 0.16 or less, more preferably 0.155 or less, and even more preferably 0.15 or less.

[35] A lubricating oil additive comprising the polymer according to any one of [1] to

[34] .

[36] A friction reducer for lubricating oil, comprising the polymer according to any one of [1] to

[34] and a solvent.

[37] The friction reducer for lubricating oils according to

[36] , wherein the solvent is a base oil.

[38] The friction reducer for lubricating oils according to

[37] , wherein the base oil is an API Group III base oil, an API Group III plus base oil, or an API Group IV base oil.

[39] The friction reducer for lubricating oil according to any one of

[36] to

[38] , wherein the content of the polymer is preferably 10 to 80 mass%, more preferably 15 to 70 mass%, and even more preferably 20 to 60 mass%, when the total mass of the lubricating oil additive is 100 mass%.

[40] A lubricating oil composition comprising the friction reducer for lubricating oil according to any one of

[36] to

[39] .

[41] The lubricating oil composition according to

[40] , wherein the content of the friction reducer for lubricating oil is preferably 0.01 to 30 mass%, more preferably 0.05 to 25 mass%, and even more preferably 0.1 to 20 mass%, when the total mass of the lubricating oil composition is 100 mass%.

[42] Use of the polymer according to any one of [1] to

[34] for producing a lubricating oil composition.

[43] Use of the polymer according to any one of [1] to

[34] for reducing friction.

[44] Use of the polymer according to any one of [1] to

[34] for improving lubricity.

[45] Use of a composition comprising the polymer according to any one of [1] to

[34] for reducing friction.

[46] Use of a composition containing the polymer according to any one of [1] to

[34] for improving lubricity.

[47] The use described in

[45] or

[46] , wherein the composition contains a solvent.

[48] ​​The use according to

[47] , wherein the solvent is a base oil.

[49] The use according to

[48] , wherein the base oil is an API Group III base oil, an API Group III plus base oil, or an API Group IV base oil.

[50] The use according to any one of

[45] to

[49] , wherein the content of the polymer is preferably 0.01 to 30 mass%, more preferably 0.05 to 25 mass%, and even more preferably 0.1 to 20 mass%, when the total mass of the composition is 100 mass%.

[0007] In addition, the present invention has the following aspects. [1] A friction reducer for lubricating oils, comprising a (meth)acrylic graft copolymer A having a main chain polymer structure and a side chain polymer structure, wherein the (meth)acrylic graft copolymer A comprises, in the side chain polymer structure, a structural unit derived from an alkyl (meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms, and a structural unit derived from a (meth)acrylate (b) represented by the following general formula (1):

[0008] [ka]

[0009] (In the formula, R 1 is a hydrogen atom or a methyl group, and R 2 represents a hydrogen atom or an organic group containing a polar group. However, the organic group containing a polar group does not include an alkoxyalkyl group. [2] The friction reducer for lubricating oils according to [1], wherein the polar group of the (meth)acrylate (b) is a hydroxyl group, a carboxyl group, an amino group or an amide group. [3] The friction reducer for lubricating oils according to [1], wherein the polar group of the (meth)acrylate (b) is a hydroxyl group. [4] The friction reducer for lubricating oils according to any one of [1] to [3], wherein the (meth)acrylic graft copolymer A further contains a structural unit derived from an alkyl (meth)acrylate (c) having an alkyl group having 1 to 10 carbon atoms. [5] The friction reducer for lubricating oils according to any one of [1] to [4], wherein the (meth)acrylic graft copolymer A contains a structural unit derived from an alkyl (meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms in the main chain polymer structure. [6] The friction reducer for lubricating oils according to any one of [1] to [5], wherein the (meth)acrylic graft copolymer A contains a constituent unit derived from a vinyl radically polymerizable monomer (m1) and a constituent unit derived from a macromonomer (M). [7] The friction reducer for lubricating oils according to [6], wherein the macromonomer (M) contains a structural unit derived from an alkyl (meth)acrylate (a) having 11 to 30 carbon atoms in the alkyl group. [8] The friction reducer for lubricating oils according to [6], wherein the macromonomer (M) has a structure represented by the following formula (2):

[0010] [ka]

[0011] (In the formula, X 1 ~X n-1 each independently represents a hydrogen atom, a methyl group, or CHOH; Y 1 ~Y n each independently represents X bonded to a vinyl group of the vinyl radical polymerizable monomer (m2) which is a monomer constituent unit of the macromonomer (M). 1 ~X n-1 Z represents a terminal group, and n represents an integer of 2 to 10,000. [9] A lubricating oil composition comprising the friction reducer for lubricating oil according to any one of [1] to [8]. Effect of the Invention

[0012] According to the polymer of the present invention, it is possible to provide a lubricating oil additive, a friction reducer for lubricating oil, and a lubricating oil composition having a high friction reducing effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention.

[0014] In the present 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.

[0015] The polymer of the present invention has a main chain polymer structure and a side chain polymer structure, the side chain polymer structure contains a structural unit derived from an alkyl (meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms, and at least one of the main chain polymer structure and the side chain polymer structure contains a structural unit derived from a (meth)acrylate (b) represented by the following general formula (1):

[0016] [ka]

[0017] (In the formula, R 1 is a hydrogen atom or a methyl group, and R 2represents a hydrogen atom or an organic group containing a polar group. However, the organic group containing a polar group does not include an alkoxyalkyl group.

[0018] The friction reducer for the lubricating oil comprises a polymer. The polymer refers to a copolymer in which at least a part of the constituent units is derived from a (meth)acrylic monomer. The polymer may further contain a constituent unit derived from a monomer other than the (meth)acrylic monomer (e.g., styrene, etc.).

[0019] The polymer is preferably a graft copolymer composed of a main chain polymer structure and a side chain polymer structure (branch polymer structure) chemically bonded to the main chain polymer structure (trunk polymer structure). In this specification, a graft copolymer is a polymer having one or more types of blocks connected as a side chain polymer structure to the main chain polymer structure. The structures of the main chain polymer and the side chain polymer may be different or the same. There is no particular limitation on the method for producing the graft copolymer, but examples thereof include a method of producing a macromonomer having a radically polymerizable double bond at its end as a side chain polymer structure, and then radically polymerizing the macromonomer with a monomer that will be a constituent unit of the main chain polymer, a method of producing a main chain polymer having a reactive site and a macromonomer having a reactive site in advance, and then reacting them, and a method of producing a side chain polymer structure by generating radicals on the main chain polymer using an initiator having hydrogen abstraction ability after producing the main chain polymer, and reacting the monomer that will be a constituent unit of the side chain polymer.

[0020] The polymer is preferably a graft copolymer that contains a structural unit derived from an alkyl (meth)acrylate (a) (hereinafter also referred to as "component (a)") having an alkyl group with 11 to 30 carbon atoms in its side chain polymer structure, and also contains a structural unit derived from a (meth)acrylate (b) (hereinafter also referred to as "component (b)") represented by the general formula (1).

[0021] Examples of the (a) component include n-undecyl (meth)acrylate, i-undecyl (meth)acrylate, n-dodecyl (meth)acrylate, i-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, i-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, i-tetradecyl (meth)acrylate, n-cetyl (meth)acrylate, i-cetyl (meth)acrylate, n-stearyl (meth)acrylate, i-stearyl (meth)acrylate, n-octadecyl (meth)acrylate, i-octadecyl (meth)acrylate, n-behenyl (meth)acrylate, i-behenyl (meth)acrylate, etc. Two or more of these may be used in combination.

[0022] As component (a), a linear or branched alkyl (meth)acrylate having 11 to 20 carbon atoms is preferred, a linear or branched alkyl methacrylate having 11 to 20 carbon atoms is more preferred, a linear or branched alkyl methacrylate having 11 to 18 carbon atoms is even more preferred, and a linear or branched alkyl methacrylate having 12 to 14 carbon atoms is particularly preferred, due to their excellent solubility in base oils and excellent friction-reducing effect.

[0023] Furthermore, since this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by reducing the viscosity of the lubricating oil composition, the content of structural units derived from component (a) is preferably 30 mass % or more, more preferably 50 mass % or more, and even more preferably 80 mass % or more, relative to the total mass of the side chain polymer structure.

[0024] Furthermore, since this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by lowering the viscosity of the lubricating oil composition, the content of structural units derived from component (a) is preferably 20 to 90 mass%, more preferably 25 to 85 mass%, and even more preferably 30 to 80 mass%, relative to the total mass of the polymer. The polymer preferably contains, as a structural unit, a structural unit derived from the component (a) also in the main chain polymer structure, since this allows the polymer to have good solubility in the base oil.

[0025] The (b) component is a (meth)acrylate represented by the following general formula (1) (hereinafter, the (meth)acrylate (b) represented by the following general formula (1) is also referred to as "polar group-containing (meth)acrylate (b)").

[0026] [ka]

[0027] (In the formula, R 1 is a hydrogen atom or a methyl group, and R 2 represents a hydrogen atom or an organic group containing a polar group. However, the organic group containing a polar group does not include an alkoxyalkyl group. Examples of the polar group include a hydroxyl group, a carboxy group, a heterocyclic structure (e.g., an aliphatic heterocycle having 2 to 6 carbon atoms, an aromatic heterocycle having 4 to 10 carbon atoms), an alkoxysilyl group, a trialkoxysilyl group having 3 to 9 carbon atoms, a phosphate group, a phosphate ester group, an amino group (e.g., secondary amino groups such as a dimethylamino group, a diethylamino group, etc.), and an amide group. Examples of the component (b) include (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate; (meth)acrylates having a carboxy group, such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; Examples of the acrylate include (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate and glycidyl (meth)acrylate; (meth)acrylates having a trialkoxysilyl group having 3 to 9 carbon atoms such as 3-(meth)acryloxypropyltrimethoxysilane and 3-(meth)acryloxypropyltriethoxysilane; (meth)acrylates having a phosphoric acid ester group such as 2-(meth)acryloyloxyethyl acid phosphate; (meth)acrylates having an amino group such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; (meth)acrylates having an amide group such as (meth)acrylamide, dimethyl(meth)acrylamide and diethyl(meth)acrylamide, etc. Two or more of these may be used in combination.The polar group-containing (meth)acrylate (b) is preferably a (meth)acrylate having a hydroxyl group or a carboxyl group, more preferably a (meth)acrylate having a hydroxyl group or a carboxyl group, more preferably a (meth)acrylate having a hydroxyl group, and particularly preferably an acrylate having a hydroxyl group. The total carbon number of the polar group-containing (meth)acrylate (b) is preferably 3 to 10, more preferably 3 to 9, and even more preferably 3 to 8.

[0028] Among organic groups having a polar group, it is more preferable to use a polar group having a large polarity. For example, a hydroxyl group, a carboxyl group, an amino group, an amide group, a phosphoric acid group, and a phosphoric acid ester group have a larger polarity than an alkoxyalkyl group, and are preferable polar groups. By having a polar group with high polarity, the polymer can improve its affinity with the metal surface by the action of intermolecular forces such as van der Waals forces and hydrogen bonds, and by the formation of chemical bonds such as covalent bonds and ionic bonds. As a result, the adhesion of the polymer to the metal surface is improved, and the friction reduction performance can be improved.

[0029] Since this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by reducing the viscosity of the lubricating oil composition, the content of the structural units derived from component (b) relative to the total mass of the polymer is preferably 0.01 mass% or more and 20 mass% or less, more preferably 0.05 mass% or more and 15 mass% or less, even more preferably 0.1 mass% or more and 5 mass% or less, and particularly preferably 0.5 mass% or more and 3 mass% or less.

[0030] The polymer preferably further contains, as a structural unit, an alkyl (meth)acrylate (c) having an alkyl group of 1 to 10 carbon atoms (hereinafter also referred to as "component (c)"), since this can improve friction reducing performance and fuel economy by reducing the viscosity of the lubricating oil composition.

[0031] Examples of the component (c) include (meth)acrylates having a linear alkyl group such as 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, and n-nonyl (meth)acrylate; i-propyl (meth)acrylate, i-butyl (meth)acrylate, and t-butyl (meth)acrylate; Examples of the methacrylate include (meth)acrylates having a branched alkyl group such as acrylate, i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; and (meth)acrylates having a cyclic alkyl group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and 4-t-butylcyclohexyl (meth)acrylate. Two or more of these may be used in combination. Because of their excellent friction-reducing effect, alkyl (meth)acrylates having 1 to 4 carbon atoms are preferred, alkyl acrylates having 1 to 4 carbon atoms are more preferred, and n-butyl acrylate is even more preferred. Since this provides an excellent friction reducing effect, it is preferable that the structural unit derived from component (c) is contained in the main chain polymer structure.

[0032] Since this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by reducing the viscosity of the lubricating oil composition, the content of the structural units derived from component (c) relative to the total mass of the polymer is preferably 20 mass% or more and 95 mass% or less, more preferably 30 mass% or more and 90 mass% or less, and even more preferably 45 mass% or more and 80 mass% or less.

[0033] In order to obtain good friction reducing performance, the total amount of the structural units derived from the components (a) to (c) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the polymer. The total amount of the structural units derived from the components (a) to (c) does not exceed 100% by mass, based on the total mass of the polymer.

[0034] The polymer may contain a structural unit derived from a radically polymerizable vinyl compound (d) (hereinafter also referred to as "component (d)") other than the components (a) to (c). Examples of the component (d) include styrene, α-methylstyrene, pt-butylstyrene, vinyl toluene, vinyl acetate, and (meth)acrylates other than the components (a) to (c). Other (meth)acrylates include (meth)acrylates having an aromatic ring structure such as 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, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, and (1-naphthyl)methyl (meth)acrylate; alkoxy (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate; trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc. These may be used in combination of two or more kinds. The polymer may contain, as structural units, structural units derived from the components (a) to (d) in either the main chain polymer structure or the side chain polymer structure.

[0035] The polymer may contain a constituent unit derived from a vinyl radical polymerizable monomer (m1) (hereinafter also referred to as "(m1) component") and a constituent unit derived from a macromonomer (M) (hereinafter also referred to as "(M) component"). The (M) component contains a constituent unit derived from a monomer (m2) having a vinyl radical polymerizable group.

[0036] Examples of the (m1) component include styrene, vinyl acetate, and (meth)acrylate compounds. Examples of the (meth)acrylate compounds 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, and n-undecyl (meth)acrylate. (Meth)acrylates having a linear alkyl group such as acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-cetyl (meth)acrylate, n-stearyl (meth)acrylate, and n-behenyl (meth)acrylate; i-propyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, and s-butyl (meth)acrylate. (meth)acrylates having a branched alkyl group such as acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, i-nonyl (meth)acrylate, i-decyl (meth)acrylate, 3-i-propylheptyl (meth)acrylate, i-undecyl (meth)acrylate, 2-t-butylheptyl (meth)acrylate, i-dodecyl (meth)acrylate, i-tridecyl (meth)acrylate, i-tetradecyl (meth)acrylate, and i-behenyl (meth)acrylate; (meth)acrylates having a cyclic alkyl group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenoxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and adamantyl (meth)acrylate;(Meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glycerin mono(meth)acrylate, ethylene glycol mono(meth)acrylate, and propylene glycol mono(meth)acrylate; (meth)acrylates containing a carboxy group, such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and phenoxydiethylene glycerin mono(meth)acrylate; (Meth)acrylates having an aromatic ring structure such as chol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, 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)acryloylmorpholine; alkoxy (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate;Examples of such acrylates include allyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and (meth)acrylamide. These may be used in combination of two or more kinds.

[0037] From the viewpoint of enhancing the friction reducing effect, it is preferable that the component (m1) contains the components (b) and (c). The (M) component is a compound containing two or more structural units derived from a monomer (m2) (hereinafter also referred to as "(m2) component") having a vinyl radical polymerizable group and having a radical polymerizable group at its terminal, and contains the (a) component as the (m2) component. Examples of the (m2) component other than the (a) component include the compounds listed as the (m1) component.

[0038] From the viewpoint of increasing the solubility of the polymer in the base oil, the (M) component preferably contains 50% by mass or more of the structural units derived from the (a) component, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on the total mass of the (M) component. The (a) component may contain 100% by mass of the structural units derived from the (a) component, but is preferably less than 100% by mass, based on the total mass of the (M) component. In order to increase the solubility of the polymer in the base oil, the structural unit derived from the component (c) is preferably contained in an amount of more than 0 mass% and not more than 20 mass%, more preferably 0.1 to 15 mass%, even more preferably 0.2 to 10 mass%, and particularly preferably 0.5 to 5 mass%, relative to the total mass of the component (M). In order to increase the solubility of the polymer in the base oil, the ratio represented by [the content of the structural units derived from the component (c)] / [the content of the structural units derived from the component (a)] is preferably from 0.001 to 3.5, more preferably from 0.002 to 3.0, and even more preferably from 0.005 to 2.6.

[0039] Furthermore, from the viewpoint of radical polymerizability, the component (M) preferably has a structure represented by the following formula (2).

[0040] [ka]

[0041] (In the formula, X 1 ~X n-1 each independently represents a hydrogen atom, a methyl group, or CHOH; Y 1 ~Y n Each of X is independently bonded to a vinyl group of the monomer structural unit (m2). 1 ~X n-1 Z represents a terminal group, and n represents an integer of 2 to 10,000.

[0042] X 1 ~X n-1 and Y 1 ~Y n are each independently a substituent bonded to the vinyl group of the component (m2). Y 1 ~Y n For example, OR 1 , halogen atom, COR 2 , COOR 3 , C.N., C.O.N. 4 R 5 , N.H.C.O.R. 6 , or R 7 R 1 ~R 7 each independently represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, or the like.

[0043] The terminal group Z may be a hydrogen atom or a group derived from a radical polymerization initiator, as in the terminal groups of polymers obtained by known radical polymerization.

[0044] In addition, from the viewpoints of increasing the solubility of the polymer in the base oil and increasing the friction reducing effect, the content of the structural units derived from the (M) component is preferably 1 to 70 mass%, more preferably 2 to 60 mass%, and even more preferably 5 to 50 mass%, relative to the total mass of the polymer.

[0045] The mass average molecular weight (Mw) of the macromonomer (M) measured by gel permeation chromatography is preferably 2,000 to 100,000, more preferably 3,000 to 80,000, even more preferably 4,000 to 50,000, and particularly preferably 5,000 to 30,000, because this can improve the solubility in base oil and the friction reducing performance, and can also improve the fuel economy by reducing the viscosity of the lubricating oil composition.

[0046] The number average molecular weight (Mn) of the macromonomer (M) measured by gel permeation chromatography (GPC) is preferably 500 to 30,000, more preferably 1,000 to 25,000, even more preferably 2,000 to 20,000, and particularly preferably 3,000 to 16,000, because this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by lowering the viscosity of the lubricating oil composition.

[0047] The molecular weight distribution (Mw / Mn) of the macromonomer (M) measured by gel permeation chromatography is preferably 1.0 to 5.0, more preferably 1.3 to 3.0, and even more preferably 1.5 to 2.5, because this can improve the solubility in base oil and the friction reducing performance, and can improve fuel economy by reducing the viscosity of the lubricating oil composition.

[0048] The (M) component may be produced by a known method or may be commercially available. Examples of the method for producing the (M) component include a method using a cobalt chain transfer agent (U.S. Pat. No. 4,680,352), a method using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (WO 88 / 04304), a method of chemically bonding a polymerizable group (JP-A-60-133007 and U.S. Pat. No. 5,147,952), and a method using thermal decomposition (JP-A-11-240854).

[0049] The method using a cobalt chain transfer agent is preferred in terms of the number of production steps and the use of a catalyst with a high chain transfer constant. Because the cobalt chain transfer agent has a high chain transfer constant, a macromonomer with a controlled molecular weight can be obtained by adding a small amount of the agent.

[0050] As the cobalt chain transfer agent, a known cobalt complex can be used. 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, relative to 100 parts by mass of the component (m2).

[0051] Furthermore, the mass average molecular weight (Mw) of the polymer contained in the friction reducer for lubricating oil of the present invention, as measured by GPC, is preferably from 10,000 to 500,000, more preferably from 15,000 to 300,000, and even more preferably from 20,000 to 200,000, because this can improve solubility in base oil and friction reducing performance, and can also improve fuel economy by reducing the viscosity of the lubricating oil composition.

[0052] Furthermore, the number average molecular weight (Mn) of polymer A contained in the friction reducer for lubricating oil of the present invention, as measured by gel permeation chromatography (GPC), is preferably from 5,000 to 100,000, more preferably from 10,000 to 80,000, and even more preferably from 15,000 to 50,000, because this can improve solubility in base oil and friction reducing performance, and can also improve fuel economy by reducing the viscosity of the lubricating oil composition.

[0053] Furthermore, the molecular weight distribution (Mw / Mn) of polymer A contained in the friction reducer for lubricating oil of the present invention, as measured by gel permeation chromatography (GPC), is preferably from 1.0 to 15, more preferably from 2.0 to 10, and even more preferably from 3.0 to 8.0, because this can improve the solubility in base oil and friction reducing performance and can also improve fuel economy by reducing the viscosity of the lubricating oil composition.

[0054] An example of the method for producing the friction reducer for lubricating oil of the present invention will be described below. The friction reducer for lubricating oil of the present invention can be produced by polymerizing a monomer mixture containing the alkyl (meth)acrylate (a) to (c) components, the other radical polymerizable vinyl compound (d) component, and the macromonomer (M) component in a base oil by a known method. The base oil is not particularly limited, but examples thereof 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.

[0055] The polymerization may be carried out under known conditions, but it is preferable to use α-methylstyrene dimer as a chain transfer agent because it is particularly effective in suppressing heat generation during polymerization.

[0056] The friction reducer for lubricating oils containing the polymer of the present invention can be used as a friction reducer for lubricating oils to be added to lubricating oils such as engine oils, drive system oils (gear oils, transmission oils), hydraulic oils, and metal processing oils used in mobility such as automobiles and ships, industrial machinery, robots, etc. Examples of base oils for the engine oil, gear oil, hydraulic oil, and the like include mineral base oils refined from crude oil and chemically synthesized synthetic oils, such as 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.

[0057] The lubricating oil composition of the present invention is obtained by blending the friction reducer for lubricating oil of the present invention with a base oil. The lubricating oil composition of the present invention may contain other additives other than the friction reducer for lubricating oil of the present invention. Examples of other additives include antioxidants, viscosity index improvers, pour point depressants, detergent dispersants, corrosion inhibitors, rust inhibitors, antifoaming agents, emulsifiers, fungicides, and antiemulsifiers. In addition, the lubricating oil composition of the present invention may contain oiliness improvers such as long-chain fatty acid esters and fatty acid amides, antiwear agents such as phosphate esters and zinc dithiophosphates, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and friction modifiers such as organic molybdenum compounds, as friction reducers other than those of the present invention. The lubricating oil composition of the present invention may be a grease containing a thickener, such as a soap-based thickener (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), an inorganic-based thickener (bentonite, silica gel, etc.), or an organic-based thickener (polyurea, polyurethane, etc.).

[0058] The content of the friction reducer for lubricating oil of the present invention contained in the lubricating oil composition is preferably 0.01 to 30 mass%, more preferably 0.05 to 25 mass%, and even more preferably 0.1 to 20 mass%, when the total mass of the lubricating oil composition is taken as 100 mass%. By making the content of the friction reducer for lubricating oil 0.01 mass% or more, the friction reducing effect of the lubricating oil composition is improved, and by making it 30 mass% or less, the kinetic viscosity of the lubricating oil composition at low temperatures is reduced, improving fuel economy.

[0059] A base oil solution containing 2 mass % of the polymer is prepared, and the friction coefficient measured at 40°C using an SRV5 testing machine (manufactured by Optimol Instruments Pruftechnik GmbH) is preferably 0.16 or less, more preferably 0.155 or less, and even more preferably 0.15 or less. EXAMPLES

[0060] 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 6, the content of the structural unit derived from each monomer is shown in mass%. The content of each structural unit was calculated from the mass of the monomer relative to the total mass of the monomers used in the polymerization reaction. Evaluation was performed by the following method.

[0061] <Molecular weight of macromonomer (M)> Measurement was performed using GPC (HLC-8320 manufactured by Tosoh Corporation). After preparing a 0.2% by mass solution of the macromonomer (M) in tetrahydrofuran, 10 μl of the above solution was injected into an apparatus equipped with columns manufactured by Tosoh Corporation (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), and measurement was performed under the conditions of 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.

[0062] <Molecular weight of polymer> Measurement was performed using GPC (HLC-8320 manufactured by Tosoh Corporation). After preparing a 0.2% by mass solution of the polymer obtained in the examples in tetrahydrofuran, 10 μl of the above solution was injected into an apparatus equipped with columns manufactured by Tosoh Corporation (2 TSKgel SuperHZM-H (inner diameter 6.0 mm, length 15 cm) and TSKguardcolumn SuperHZ-H (inner diameter 4.6 mm, length 3.5 cm), and measurement was performed under the conditions of a flow rate of 0.5 ml / min, eluent: tetrahydrofuran (stabilizer BHT), and column temperature: 40° C., and Mw, Mn, and Mw / Mn were calculated in terms of standard polystyrene.

[0063] <Friction coefficient at 40℃> The obtained polymer, YUBASE4, and MoDTC (molybdenum dialkyldithiocarbamate) were mixed for 10 minutes while heating to 65°C in the compositions shown in Tables 2 to 6 to prepare lubricating oil compositions, and the friction coefficients at 40°C were measured using an SRV5 tester (manufactured by Optimol Instruments Pruftechnik GmbH). The measurement conditions were as follows, and the friction coefficients were evaluated 30 minutes after the start of the measurement. Test method: Ball-on-disc (ball diameter: 10mm, ball and disc material: SUJ2) Test mode: round trip (50Hz, stroke 1mm) Load capacity: 200N

[0064] [Production Example 1] (Synthesis of Co complex (cobalt chain transfer agent)) In a synthesis apparatus equipped with a stirrer, 2.00 g (8.03 mmol) of cobalt (II) acetate tetrahydrate (Wako Pure Chemical Industries, Ltd., Wako special grade), 3.86 g (16.1 mmol) of diphenylglyoxime (Tokyo Chemical Industry Co., Ltd., EP grade), and 100 ml of diethyl ether that had been deoxygenated in advance by nitrogen bubbling were placed 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 Industry Co., Ltd., EP grade) was added and stirred for another 6 hours. The obtained product was filtered, and the solid was washed with diethyl ether and dried at 100 MPa or less at 20°C for 12 hours to obtain 5.02 g (7.93 mmol, yield 99% by mass) of a brown solid Co complex.

[0065] [Production Example 2] (Synthesis of Macromonomer M1) A reaction vessel equipped with a stirrer, a cooling tube, and a thermometer was charged with 58 parts of YUBASE4, 98 parts of Acrylate SL (manufactured by Mitsubishi Chemical Corporation, product name: Acrylate SL, a mixture of an alkyl methacrylate having an alkyl group with 12 carbon atoms and an alkyl methacrylate having an alkyl group with 13 carbon atoms), 2 parts of methyl methacrylate (MMA) (manufactured by Mitsubishi Chemical Corporation, product name: Acrylate M), and 0.005 parts of the Co complex prepared in Production Example 1. The liquid temperature was raised to 40°C, and nitrogen was bubbled through the mixture for 2 hours while stirring to remove dissolved oxygen. A mixture of YUBASE4 (2 parts) and 0.1 parts of t-butylperoxy-2-ethylhexanoate (Arkema Yoshitomi Co., Ltd., product name: Luperox 26) as a polymerization initiator was added, the liquid temperature was raised to 90 ° C., and 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 dropping, the temperature was raised to 105 ° C. and held for 1.5 hours, 20 parts of YUBASE4 were added and cooled, and a YUBASE4 solution containing 52.6 mass% of macromonomer M1 was obtained. The results of GPC of the obtained macromonomer M1 are shown in Table 1.

[0066] [Production Example 3] (Synthesis of macromonomer M2) A reaction vessel equipped with a stirrer, a cooling tube and a thermometer was charged with 58 parts of YUBASE4, 98 parts of Acrylate SL, 2 parts of MMA and 0.005 parts of the Co complex prepared in Production Example 1, and the liquid temperature was raised to 40°C. Nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixture of YUBASE4 (2 parts) and 0.1 parts of t-amylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 575) as a polymerization initiator was added, the liquid temperature was raised to 90°C, and 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 dropping, the temperature was raised to 105°C and held for 1.5 hours, and then 20 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M2. The results of GPC of the obtained macromonomer M2 are shown in Table 1.

[0067] [Production Example 4] (Synthesis of macromonomer M3) In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 58 parts of YUBASE4, 98 parts of Acrylate SL, 2 parts of MMA, and 0.0075 parts of the Co complex prepared in Production Example 1 were added, and the liquid temperature was raised to 40°C. Nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixture consisting of YUBASE4 (2 parts) and 0.1 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (manufactured by NOF Corp., trade name: Perocta O) as a polymerization initiator was added, the liquid temperature was raised to 83°C, and after stirring for 2.5 hours, a mixture consisting of YUBASE4 (10 parts) and Perocta O (0.7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 95°C and held for 2 hours, after which 20 parts of YUBASE4 were added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M3. The results of GPC of the obtained macromonomer M3 are shown in Table 1.

[0068] [Production Example 5] (Synthesis of macromonomer M4) In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 58 parts of YUBASE4, 2 parts of methyl methacrylate (MMA) (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester M), 98 parts of stearyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Lightester S), and 0.005 parts of the Co complex prepared in Production Example 1 were added, and the liquid temperature was raised to 40°C. Nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixture of YUBASE4 (2 parts) and 0.2 parts of t-butylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 26), which is a polymerization initiator, was added, and the liquid 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 maintained for 1.5 hours, after which 20 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M4. The results of GPC of the obtained macromonomer M4 are shown in Table 1.

[0069] [Production Example 6] (Synthesis of macromonomer M5) In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 58 parts of YUBASE4, 100 parts of 2-ethylhexyl methacrylate, and 0.003 parts of the Co complex prepared in Production Example 1 were added, and the liquid temperature was raised to 40°C. Nitrogen was bubbled for 2 hours while stirring to remove dissolved oxygen. A mixture consisting of YUBASE4 (2 parts) and 0.1 parts of t-amylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., product name: Luperox 575) as a polymerization initiator was added, the liquid temperature was raised to 90°C, and after stirring for 2.5 hours, a mixture consisting of YUBASE4 (10 parts) and Luperox 575 (0.7 parts) was added dropwise over 1 hour. After dropping, the temperature was raised to 105°C and held for 1.5 hours, and then 20 parts of YUBASE4 were added and cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M5. The results of GPC of the obtained macromonomer M5 are shown in Table 1.

[0070] <Example 1> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2, 56 parts of n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: nBA), 18 parts of lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: LA), 1 part of 4-hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name: 4HBA), 0.03 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name: Perbutyl O) as a polymerization initiator, and 0.3 parts of α-methylstyrene dimer (manufactured by NOF Corporation, trade name: Nofumer MSD) as a chain transfer agent were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C and maintained for 3.5 hours, and then a mixture consisting of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. After further maintaining at 85°C for 1 hour, a mixed liquid consisting of YUBASE4 (30 parts) and PERBUTYL O (0.5 parts) was added dropwise over 1 hour. The temperature was then raised to 110°C and maintained for 1 hour, after which 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35 mass% of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 2. In Tables 2 to 6, the polymer composition also includes the constituent units in the macromonomer (M).

[0071] <Example 2> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0072] <Example 3> When preparing a lubricating oil composition using the friction reducer for lubricating oil obtained in Example 2, MoDTC was added and used for evaluation in the ratio shown in Table 2. The evaluation results of the obtained lubricating oil composition are shown in Table 2.

[0073] <Example 4> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3, 56 parts of nBA, 18 parts of LA, 1 part of 4HBA, 0.03 parts of Perbutyl O, and 0.5 parts of Nofumer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The liquid temperature was raised to 85°C and held for 3.5 hours, and then 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 (30 parts) and Perbutyl O (0.5 parts) was added dropwise over 1 hour. The temperature was then raised to 110°C and held for 1 hour, after which 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0074] <Example 5> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0075] <Example 6> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M3 obtained in Production Example 4 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0076] <Example 7> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (44 parts), LA (30 parts), 4HBA (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.3 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0077] <Example 8> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), LA (65 parts), 4HBA (10 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.4 parts) was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 2.

[0078] <Example 9> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 9.5 parts of the YUBASE4 solution of macromonomer M2 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 (69 parts), LA (22 parts), 4HBA (4 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (76.2 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 2.

[0079] <Example 10> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 95.1 parts of the YUBASE4 solution of macromonomer M2 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 of YUBASE4 (25 parts), nBA (48 parts), 4HBA (2 parts), Luperox 575 (0.1 parts), and Nofumer 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 Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110 ° C. and holding for 1 hour, YUBASE4 (35.6 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 2.

[0080] <Example 11> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), hydroxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., trade name: HEA) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0081] <Example 12> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), HEA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.7 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 3 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0082] <Example 13> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (55 parts), LA (17 parts), HEA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.7 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0083] <Example 14> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), glycerin monomethacrylate (manufactured by NOF Corporation, trade name: Blenmar GLM) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.4 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0084] <Example 15> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (18 parts), Blenmar GLM (2 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.6 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0085] <Example 16> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (18 parts), Blenmar GLM (2 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.6 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0086] <Example 17> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), acrylic acid (manufactured by Mitsubishi Chemical Corporation, trade name: AA) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.6 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil are shown in Table 3.

[0087] <Example 18> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), AA (3 parts), Luperox 575 (0.1 parts), and Nofumer 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 Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 3.

[0088] <Example 19> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), AA (3 parts), Luperox 575 (0.1 parts), and Nofumer 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 Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 3.

[0089] <Example 20> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85 ° C., and a mixture of YUBASE4 (25 parts), LA (65 parts), AA (10 parts), Luperox 575 (0.1 parts), and Nofumer 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 Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110 ° C. and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 4.

[0090] <Example 21> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), diethylacrylamide (KJ Chemicals, trade name: DEAA) (1 part), Luperox 575 (0.4 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and maintaining for 2 hours, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 4 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0091] <Example 22> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (54 parts), LA (16 parts), DEAA (5 parts), Luperox 575 (0.4 parts), and Nofumer 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 Luperox 575 (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 cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 4.

[0092] <Example 23> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85 ° C., and a mixture consisting of YUBASE4 (25 parts), nBA (54 parts), LA (16 parts), DEAA (5 parts), Luperox 575 (0.4 parts), and Nofumer 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 Luperox 575 (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 cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 4.

[0093] <Example 24> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (56 parts), LA (18 parts), polypropylene glycol monomethacrylate (manufactured by NOF Corporation, trade name: Blenmar PP-800, average number of moles of propylene oxide added: 13, terminal: hydroxyl group) (1 part), Luperox 575 (0.4 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 95°C and holding for 2 hours, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 4.

[0094] <Example 25> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (54 parts), LA (16 parts), Blenmar PP-800 (5 parts), Luperox 575 (0.4 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and maintaining for 2 hours, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 4 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0095] <Example 26> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (54 parts), LA (16 parts), Blenmar PP-800 (5 parts), Luperox 575 (0.4 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 95°C and maintaining for 2 hours, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 4 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0096] <Example 27> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (56 parts), LA (18 parts), 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM503) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.7 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer are shown in Table 4.

[0097] <Example 28> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (55 parts), LA (17 parts), 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM503) (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.7 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer are shown in Table 4.

[0098] <Example 29> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (18 parts), 4HBA (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 4 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0099] <Example 30> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 obtained in Production Example 3 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0100] <Example 31> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (18 parts), HEA (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (1.2 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0101] <Example 32> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (55 parts), LA (17 parts), HEA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0102] <Example 33> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M3 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 (56 parts), LA (18 parts), 4HBA (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0103] <Example 34> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M3 obtained in Production Example 4 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4HBA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0104] <Example 35> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M3 obtained in Production Example 4 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), HEA (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (1.2 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0105] <Example 36> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M3 obtained in Production Example 4 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), HEA (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (1.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0106] <Example 37> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), dimethylaminoethyl acrylate (manufactured by Toa Gosei Co., Ltd., trade name: Aron DA) (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 5 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0107] <Example 38> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 95.1 parts of the YUBASE4 solution of macromonomer M2 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 (49 parts), polyethylene glycol monoacrylate (addition mole number of ethyleneoxy group: about 4.5, NOF Corporation, product name: AE-200) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 110°C and holding for 1 hour, YUBASE4 (35.6 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 5.

[0108] <Example 39> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 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), nBA (56 parts), LA (18 parts), polyethylene glycol monoacrylate (addition mole number of ethyleneoxy group: about 10, NOF Corporation, trade name: AE-400) (1 part), Luperox 575 (0.4 parts), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 5.

[0109] <Example 40> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled through while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), polypropylene glycol monoacrylate (molar number of propyleneoxy groups added: about 6, NOF Corporation, trade name: AP-400) (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After heating to 110°C and holding for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 6.

[0110] <Example 41> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M4 obtained in Production Example 5 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), 4-hydroxybutyl acrylate (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0111] <Example 42> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4-hydroxybutyl acrylate (3 parts), Luperox 575 (3 parts), and Nofumer MSD (4 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0112] <Example 43> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M2 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 (55 parts), LA (17 parts), 4-hydroxybutyl acrylate (3 parts), Luperox 575 (1 part), and Nofumer MSD (1.9 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0113] <Example 44> In a reaction vessel equipped with a stirrer, a cooling tube, and a thermometer, 40 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85 ° C., and a mixture consisting of YUBASE4 (25 parts), nBA (55 parts), LA (17 parts), 4-hydroxybutyl acrylate (3 parts), and Luperox 575 (0.1 parts) was added dropwise over 4 hours. After holding at 85 ° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110 ° C. and holding for 1 hour, YUBASE4 (48.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35 mass% of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 6.

[0114] <Example 45> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 95.1 parts of the YUBASE4 solution of macromonomer M2 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 (47 parts), 4-hydroxybutyl acrylate (3 parts), Luperox 575 (0.1 parts), and Nofumer MSD (1.3 parts) was dropped over 4 hours. After holding at 85 ° C. for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was dropped over 1.5 hours. After raising the temperature to 110 ° C. and holding for 1 hour, YUBASE4 (35.6 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 6.

[0115] <Example 46> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 133.1 parts of the YUBASE4 solution of macromonomer M2 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 of YUBASE4 (30 parts), nBA (27 parts), 4-hydroxybutyl acrylate (3 parts), Luperox 575 (1 part), and Nofumer MSD (0.9 parts) was added dropwise over 4 hours. After holding at 85 ° C. for 1 hour, a mixture of YUBASE4 (20 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110 ° C. and holding for 1 hour, YUBASE4 (44.5 parts) was added and cooled to obtain a YUBASE4 solution containing 35 mass% of polymer. The evaluation results of the lubricating oil composition containing the obtained friction reducer for lubricating oil are shown in Table 6.

[0116] <Comparative Example 1> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 50 parts of YUBASE4, 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2, 56 parts of nBA, 19 parts of LA, 0.03 parts of Perbutyl O, and 0.05 parts of Nofumer MSD were added, and dissolved oxygen was removed by bubbling nitrogen while stirring. The liquid temperature was raised to 85°C and held for 3.5 hours, and then 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 (30 parts) and Perbutyl O (0.5 parts) was added dropwise over 1 hour. After that, the temperature was raised to 110°C and held for 1 hour, and then 41.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0117] <Comparative Example 2> A reaction vessel equipped with a stirrer, a cooling tube and a thermometer was charged with 72.6 parts of YUBASE4, 44 parts of nBA, 30 parts of LA, 24.5 parts of Acrylate SL, 0.5 parts of MMA, 1 part of 4HBA, 0.03 parts of Perbutyl O, and 0.15 parts of Nofumer MSD, and dissolved oxygen was removed by bubbling nitrogen while stirring. The liquid temperature was raised to 85°C, and after holding for 3.5 hours, a mixture of YUBASE4 (42 parts) and Perbutyl O (0.015 parts) was added dropwise over 2 hours. After 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 110°C and held for 1 hour, after which 11.1 parts of YUBASE4 was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0118] <Comparative Example 3> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M1 obtained in Production Example 2 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), 2-methoxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., trade name: 2-MTA) (1 part), Luperox 575 (1 part), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0119] <Comparative Example 4> In a reaction vessel equipped with a stirrer, a cooling tube and a thermometer, 30 parts of YUBASE4 and 47.6 parts of the YUBASE4 solution of macromonomer M5 obtained in Production Example 6 were added, and nitrogen was bubbled while stirring to remove dissolved oxygen. The liquid temperature was raised to 85°C, and a mixture consisting of YUBASE4 (25 parts), nBA (56 parts), LA (18 parts), 4-hydroxybutyl acrylate (1 part), Luperox 575 (0.1 parts), and Nofumer MSD (0.5 parts) was added dropwise over 4 hours. After maintaining at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and maintaining it for 1 hour, YUBASE4 (58.1 parts) was added and cooled to obtain a YUBASE4 solution containing 35% by mass of polymer. Table 6 shows the evaluation results of the lubricating oil compositions containing the obtained friction reducers for lubricating oil.

[0120] In Comparative Example 1, the polymer did not contain a constituent unit derived from component (b), and therefore the friction coefficient was high. In Comparative Example 2, the polymer did not have a side chain polymer structure, and therefore the friction coefficient was high. In Comparative Example 3, the polymer contained a constituent unit having an alkoxyalkyl group as a polar group, but did not contain a constituent unit derived from component (b), and therefore the friction coefficient was high like in Comparative Example 1. In Comparative Example 4, the side chain polymer structure did not contain a constituent unit derived from component (a), and therefore the friction coefficient was high.

[0121] [Table 1]

[0122] [Table 2]

[0123] [Table 3]

[0124] [Table 4]

[0125] [Table 5]

[0126] [Table 6]

[0127] The abbreviations in Tables 1 to 6 are as follows. SLMA: A mixture of an alkyl methacrylate with an alkyl group having 12 carbon atoms and an alkyl methacrylate with an alkyl group having 13 carbon atoms (manufactured by Mitsubishi Chemical Corporation, product name: Acryester SL) MMA: Methyl methacrylate (Mitsubishi Chemical Corporation, product name: Acryester M) SMA: Stearyl methacrylate (Kyoeisha Chemical Co., Ltd., product name: Light Ester S) EHMA: 2-Ethylhexyl methacrylate (manufactured by Mitsubishi Chemical Corporation, product name "Acryester EH") M1: Macromonomer synthesized in Example 2 M2: Macromonomer synthesized in Example 3 M3: Macromonomer synthesized in Example 4 M4: Macromonomer synthesized in Example 5 M5: Macromonomer synthesized in Example 6 LA: Lauryl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name: LA) 4HBA: 4-Hydroxybutyl acrylate (Mitsubishi Chemical Corporation, product name: 4HBA) HEA: Hydroxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name: HEA) GLM: Glycerin monomethacrylate (NOF Corporation, product name: Blenmer GLM) AA: Acrylic acid (manufactured by Mitsubishi Chemical Corporation, product name: acrylic acid) DEAA: Diethylacrylamide (KJ Chemicals, product name: DEAA) PP800: Polypropylene glycol monomethacrylate (NOF Corporation, product name: Blenmer PP-800, average number of moles of propylene oxide added: 13, terminal: hydroxyl group) KBM503: 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM503) Aron DA: Dimethylaminoethyl acrylate (manufactured by Toagosei Co., Ltd., product name: Aron DA) AE-200: Polyethylene glycol monoacrylate (number of moles of ethyleneoxy group added: approx. 4.5, NOF Corporation, product name: Blenmar AE-200) AE-400: Polyethylene glycol monoacrylate (number of moles of ethyleneoxy groups added: approximately 10, manufactured by NOF Corporation, product name: Blenmar AE-400) AP-400: Polypropylene glycol monoacrylate (number of moles of propyleneoxy groups added: approximately 6, NOF Corporation, product name: Blenmar AP-400) nBA: n-Butyl acrylate (manufactured by Mitsubishi Chemical Corporation, product name: butyl acrylate) 2-MTA: 2-Methoxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name: 2-MTA) [Industrial Applicability]

[0128] According to the polymer of the present invention, it is possible to provide a lubricating oil additive, a friction reducer for lubricating oil, and a lubricating oil composition having a high friction reducing effect.

Claims

1. A lubricating oil additive comprising a lubricating oil additive polymer, The polymer for lubricating oil additives has a main chain polymer structure and a side chain polymer structure, the side chain polymer structure contains a structural unit derived from an alkyl (meth)acrylate (a) having an alkyl group with 11 to 30 carbon atoms, At least one of the main chain polymer structure and the side chain polymer structure contains a structural unit derived from a (meth)acrylate (b) represented by the following general formula (1): the polar group of the (meth)acrylate (b) is a hydroxyl group, a carboxyl group, an amino group, or an amide group; the proportion of the side chain polymer structure is 2 to 75% by mass based on the total mass of the polymer, the content of structural units derived from the alkyl (meth)acrylate (a) component having an alkyl group with a carbon number of 11 to 30 is 30 mass% or more relative to the total mass of the side chain polymer structure, The content of structural units derived from an alkyl (meth)acrylate (a) component having an alkyl group with 11 to 30 carbon atoms is 20 to 90 mass % based on the total mass of the polymer. 【Chemistry 1】 (In the formula, R １ is a hydrogen atom or a methyl group, R ２ represents a hydrogen atom or an organic group containing a polar group. However, the organic group containing a polar group does not include an alkoxyalkyl group.

2. 2. The lubricating oil additive of claim 1, wherein the polar group of the (meth)acrylate (b) is a hydroxyl group.

3. The lubricating oil additive according to claim 1, further comprising a structural unit derived from an alkyl (meth)acrylate (c) having an alkyl group having 1 to 10 carbon atoms.

4. The lubricating oil additive according to claim 1, wherein the main chain polymer structure contains a constitutional unit derived from an alkyl (meth)acrylate (a) having an alkyl group having 11 to 30 carbon atoms.

5. the main chain polymer structure contains a constituent unit derived from a vinyl radical polymerizable monomer (m1), and at least a part of the constituent unit derived from the vinyl radical polymerizable monomer (m1) is a constituent unit derived from the (meth)acrylate (b); The lubricating oil additive of claim 1.

6. The lubricating oil additive according to claim 5 , wherein the side chain polymer structure comprises a constitutional unit derived from a macromonomer (M).

7. The lubricating oil additive according to claim 6, wherein the macromonomer (M) contains a structural unit derived from an alkyl (meth)acrylate (a) having an alkyl group having 11 to 30 carbon atoms.

8. The lubricating oil additive according to claim 6, wherein the macromonomer (M) has a structure represented by the following formula (2): 【Chemistry 2】 (In the formula, X １ ~X ｎ－１ are each independently a hydrogen atom, a methyl group, or CH ２ OH, Y １ ~Y ｎ each independently represents X bonded to a vinyl group of the vinyl radical polymerizable monomer (m2) which is a monomer constituent unit of the macromonomer (M). １ ~X ｎ－１ Z represents a terminal group, and n represents an integer of 2 to 10,000.

9. A friction reducer for lubricating oil, comprising the lubricating oil additive according to any one of claims 1 to 8, and a solvent.

10. A lubricating oil composition comprising the friction reducer for lubricating oils according to claim 9.

11. 10. The friction reducer for lubricating oils according to claim 9, wherein the solvent is a base oil.

12. A lubricating oil composition comprising the friction reducer for lubricating oils according to claim 11.

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